Electric alarm clock mechanism



March 1955 c. v. POMATTO ET AL ELECTRIC ALARM CLOCK MECHANISM 3 Sheets-Sheet 2 Filed Oct. 15, 1952 NVBNTQ CHARLES V. POMATTO MAX E. SCHLENKER BY We? fl Cflr-romoe-Y March 1955 c. v. POMATTO ET AL 2,704,432

ELECTRIC ALARM CLOCK MECHANISM Filed Oct. 13, 19:2 3 Sheets-Sheet s CHARLES V. POMATTO MAX E. SCHLENKER CHTTOIQNBY/ United States Patent i ELECTRIC ALARM CLOCK MECHANISM Charles V. Pomatto, Liverpool, N. Y., and Max E.

bchlenker, Peru, 1ll., assignors to General Time Corporation, New york, N. 1., a corporation of Delaware Application October 13, 1952, Serial No. 314,418

11 Claims. (Cl. 58-38) The present invention relates to electric alarm clocks, and more particularly to an improved electromagnetic vibrator arrangement.

blCCLIlC alarm ClOCKS are known in the art in which a single coil 1S used to drive the rotor and to vibrate the armature or the alarm, I01 example, as shown in lisseyre et a1. ratent 4004421 and in L..0Wl6S ratent Z.,UUZ.,4.$5. in general, sucn arrangements have been applicable to the open-con type or motor. A number or attempts have been made to apply a so-called "buzzer alarm" to a clock having an enclosed coll motor, but without significant success. One such attempt is snown in the Kelly ratent 2,417,254. A ma or dithculty has been the coupling of the armature to the magnetic poles or' the motor without loss of motor torque. even a small percentage loss is an important factor, since cloclt motors or the most up-todate design have little torque to spare and cannot sacrifice torque without sacrificing reliability.

Accordingly, it is an ob ect to provide an electric alarm cloclc mechanism having a single coil for both driving and ringing purposes, which has a high degree or reliability and improved torque characteristics. it is another object to provide an electric alarm mechanism in which the electromagnetic ringing structure does not substantially affect the motor torque. it is a more detailed object to provide an improved electric alarm clock motor of the closed-coil type in which the ringing is elfected by poles located outside of the motor field and which is highly efficient, requiring a minimum of energy from the magnetic circuit of the motor. it is a related object to provide a motor of the closed-coil type having an electromagnetic ringing arrangement in which unbalance of flux distribution and the short-circuiting of flux is reduced to a minimum under conditions of ringing and shut-off, and which is completely free of noise or vibration in the condition of shut-ctr. It is also an object to provide an electric alarm clock of the above type which requires minimum modification of existing designs of closed-coil motors and which may be constructed simply and cheaply.

Other objects and advantages of the invention will become apparent upon reading the attached specification and upon reference to the drawings, in which Figure 1 is a general view in elevation of an electric alarm clock mechanism employing the present invention.

Fig. 2 is an enlarged sectional view of the closed-coil motor and pole pieces taken along the line 22 of Fig. 1.

Fig. 3 is a detailed fragmentary view of the armature construction and shut-01f arrangement.

Fig. 4 is a view similar to Fig. 3 showing the armature manually shut off.

F Figl. 5 is a detailed view taken along the line 5-5 of Fig. 6 is fragmentary view of the shut-01f lever and clock-driven cam.

Fig. 7 is a fragmentary sectional view of the clockdriven cam taken along the line 77 of Fig. 3.

Fig. 8 is a sectional view of the loudness adjustment taken along the line 88 of Fig. 3.

Fig. 9 shows the pole pieces isolated from the motor.

. Fig. 10 shows the spacing of the pairs of shaded and unshaded poles in the present motor.

While the invention is susceptible of various modifications and alternative constructions and uses, it will be understood that we have illustrated and will describe herein only the preferred embodiment. The invention is, however, not limited to this preferred embodiment, but

2,704,432 Patented Mar. 22, 1955 covers all alternative constructions falling within the spirit and scope or the appended claims.

.Kelfilfllllg now to rlgure l, the 610614 mechamsm indicated generally at 40 includes a rrame 1.1 and a motor 22 01' the closed-coll type. '1he motor orlves a 610GB. train 2's, only a portion or which is snown 1n rig. 2. it will be understood that the ClOCK train 18 or conventional type having [116 usual 110111 and LLLLllLlLG ndnUS \UUL S110 WD.) 'culu may, A1. desired, be adapted [or any other timing or COIlLl'Ol. PLIIPOSfi. 1H6 CLOCK IHCCHBIllSlD also lllClUUCS an armature assembly 24, ror strutmg an alarm hell 2:. The motor :42 which is utilized in the present invention is an improvement over the motor which is described in detail in schlenlser et al. latent 2,337,095 which issued on January y, 1731, and rererence is made to this patent for a description or common elements. lt will sulnce to say that the motor includes an outer stator element :0 which is or' cup shape, having a base 31 and a set or poles 32 which are integral with the base and WILlCll extend parallel to one another to rorm the outer shell or the motor. in the present construction, the outer stator element includes seven pairs or poles designated 41-4 7, mclusive (rig. l0). leach pair or poles includes a shaded pole and an unshaded pole, shading being provided by a copper shading plate 46. l axing the pair of poles 41 by way of example, the unshaded pole is indicated at 41a and the shaded pole at 411).

Recessed within the outer stator element is a toroidal coil 50 having a cylindrical core 51. it will be noted in the sectional view, rig. 2, that the poles of the stator extend axially beyond the coil. Mounted at the right-hand end of the core 51 is an inner stator element 52, which includes an unshaded pole piece a: and a shaded pole piece :4, shading being provided by copper shading rings 55. The inner stator element is of generally circular connguration providing a set of poles 60, which face outwardly toward the set of poles 32. The pairs or poles have been designated at 61-68, inclusive. Similarly to the outer poles, each unshaded pole may be referred to by the subscript a and each shaded pole by the subscript b.

Mounted in the annular space between the two sets of poles is a rotor 70, rotating on bearings 71, 72. The rotor 70 has a peripheral portion 73 which is of magnetic material having a high hysteresis characteristic. Mounted at the end of the rotor shaft is a pinion '74 which engages the input gear of the clock train 23. Although only a portion of the clock train 23 has been shown, the construction and arrangement of the train is well within the scope of one skilled in this art.

In accordance with the present invention, the motor 22 is provided with first and second pole pieces 81, 82. These pole pieces are in the form of flat strips of magnetic material which engage the ends of the core and which extend outwardly from the motor in parallel relation, as shown in Figs. 2 and 9. At their outer ends the pole pieces 81, 82 provide spaced poles 83, 84. These pole pieces 81 and 82 are referred to hereinafter and in the claims as ringing pole pieces.

Further in accordance with the invention, the pole piece 82 lies flatly adjacent the coil 50 and extends outwardly through an opening provided between two adjacent pairs of poles on the outer stator element. As shown in Figs. 1 and 10, these pairs of poles are indicated at 41, 47, respectively. In carrying out the invention the pairs of poles 4147 are all spaced the same angular distance A from one another; however, the pairs of poles 41, 47, which lie on opposite sides of the pole piece 82 are spaced apart by double this amount, namely, 2A. The pairs of poles 61-68 on the inner stator element are each spaced apart an angular amount A corresponding to the poles Referring now to the armature assembly 24, such assembly includes an armature 90, which is dimensioned to swing between the poles 83, 84, as shown in Fig. 2. This armature is freely mounted on an armature spring 91, which is anchored at one end 92 and which carries a clapper 93 at its opposite end. The armature spring 91 is preferably designed so that its natural period coincides with the natural period of the exciting flux. For the purpose of varying the amplitude of vibration, an adjust able damper is provided. This damper includes a damper arm 95 having a resilient button 96 at its outer end which engages the back side of the spring 91. The damper arm is biased toward the armature by a spring 97 and is manually positioned by means of a cam 98. The cam 98 is mounted for rotation by a knurled knob 99, as shown in Fig. 8, so that manual adjustment of loudness may be readily effected.

In accordance with a more detailed aspect of the present invention, improved means are provided for shutting off the alarm. This is accomplished as shown in Figs. 3-6, by a shut-off lever 100. This lever includes a shut-off arm 101, a clock controlled arm 102 and a manually controlled arm 103. When the shut-off lever 100 is rotated in the clockwise direction, as shown in Fig. 4, the end of the shut-off arm 101 directly engages the armature 90 and moves it away from the poles 83, 84. In the position of shut-E the damper arm 95 is raised against a stop 104 so that the armature is securely clamped between the arm 101 and the resilent button 96 (see Fig. 4). This insures silence and freedom of vibration during shutoff. For manual shut-off a plunger 106 is provided having a cam 107. This plunger is movable between a retracted position in which the armature is free to move and a de pressed position in which the cam 107 engages the arm 103.

To obtain clock control of the armature at a preset time a clock-driven cam 110 is provided for engaging the arm 102. As shown in Figs. 6 and 7, the cam 110 is conical in shape and is driven synchronously with the hour hand of the clock by means of a gear 111. The cam 110 presents a helical cam surface 112 which is engaged by a cam follower pin 113. This pin normally holds the cam in its inner position against the biasing force of the spring 115, with the cam occupying a position indicated by the dotted outline 116. The resulting engagement between the cam and the clock controlled arm 102 holds lever 100 in its position of shut-off. However, as soon as the drop-off point 114 of the cam is reached, the cam 110 springs to the right, freeing the shut-off lever 100 so that vibration of the armature may take place freely. The point of drop-off may be adjusted for a particular hour by changing the position of the cam follower pin 113. This is accomplished in the present embodiment by mounting the pin 113 rotatably on an adjustable setting shaft 117, which may be manually adjusted relative to a calibrated alarm scale as will be apparent to one skilled in the art.

In accordance with one of the more detailed aspects of the invention, an indicator is provided for indicating power failure in response to the magnetism in the pole pieces 81, 82. This indicator indicated at 120 includes pole piece 82. As shown in Fig. 9, the extension 82a is bent over in the direction of the companion pole piece 81. It is, however, located remotely from the poles 83, 84. In operation, the indicator armature 121 is gravity biased into an off position indicated at 121a. However, upon applying power to the motor and upon manually moving the armature 121 into its attracted position by bodily rotating the clock, the indicator will remain stably in its attracted position until a power failure occurs. It is found that the pole extension 82a does not tend to divert any appreciable amount of magnetism from the pole 81 to the pole 82. And being located at some distance from the vibrating armature 90, the extension 82a has no effect upon the field of the vibrating armature.

The closed-coil motor and its electromagnetic ringing arrangement has been found to possess a number of unexpected and important operating advantages. In the first place, it should be pointed out that the synchronous speed is unaffecteed by the elimination of one pole from the outer stator. The formula for synchronous speed is usually stated to be the quotient of the cycles per minute divided by the number of pairs of poles acting on the rotor. In the present motor the synchronous speed is 450 R. P. M., at a current frequency of 60 cycles per second, the same as in a more conventional 16 pole motor, such as is described in the Schlenker et al. patent previously referred to.

The torque of the motor is not seriously affected by the elimination of one pole. It has been found to be ample for alarm clock and time switch applications.

A further operating advantage of the present construction is that the armature spring 91 is mounted for free vibration of the armature so that frictional forces do not have to be overcome. This is true even though the amplitude of vibration is varied over relatively wide limits by the damper arm 95.

Another feature of the construction is freedom from noise and vibration under the condition of shut-oif, which is contrasted with previous attempts to utilize a closedcoil motor where unwanted vibration has been present to a high degree.

We claim as our invention:

1. In an electric alarm clock, the combination comprising a toroidal coil having a central core, a first stator element of cup shape surrounding said coil and providing a first set of poles at its periphery and extending axially beyond said coil, a second stator element on top of said coil and providing a second set of poles arranged in circular configuration at its periphery, a rotor symmetrically mounted for rotation adjacent said sets of poles, a first pole piece magnetically coupled to the end of said central core remote from the rotor and extending radially outward between adjacent pairs of poles on said outer stator elcment, a second pole piece lying substantially parallel to the first pole piece and magnetically coupled to the end of the core nearest to the rotor, an armature magnetically coupled to said pole pieces and mounted for vibration with respect thereto, and means for releasing said armature for vibration.

2. In an electric alarm clock, the combination comprising a toroidal coil having a central core, an outer stator element of cup shape surrounding said coil and providing a first set of poles at its periphery and extending axially beyond said coil, an inner stator element on top of said coil and providing a second set of poles arranged in circular configuration at its periphery, a rotor symmetrically mounted for rotation between the respective sets of poles, pole pieces at the respective ends of said central core and extending radially outward beyond said outer stator element, an armature magnetically coupled to said pole pieces and mounted for vibration with respect thereto, and means including a clock train for releasing said armature for vibration.

3. In an electric alarm clock, the combination comprising a toroidal coil having a central core, an outer stator element of cup shape surrounding said coil and providing a first set of poles at its periphery, an inner stator element on top of said coil and providing a second set of poles arranged in a circle at its periphery, a

rotor symmetrically mounted for rotation between therespective sets of poles, pole pieces at the respective ends of said central core and extending radially outward parallel to one another and beyond said outer stator element to provide a pair of spaced poles, and an armature magnetically coupled to said spaced poles and mounted for vibration in response to the varying field thereof.

4. In an electric alarm clock, the combination comprising a torodial coil having a central core, an outer stator element of cup shape surrounding said coil and providing a spaced set of poles at its periphery, a rotor mounted coaxially with respect to said core and having an outer peripheral portion magnetically coupled to said set of poles, a pole piece lying between said coil and said rotor and in intimate magnetic engagement with said core at its inner end and providing a ringing pole at its outer end remote from said rotor, the poles comprising a set being arranged in spaced pairs each pair having a shaded pole and an unshaded pole, said pairs being spaced a unit distance apart around the periphery of the rotor except that the pairs of poles lying on opposite sides of the ringing pole piece are spaced two units apart, and means including an armature magnetically coupled to said ringing pole piece and mounted for vibration in response to the varying field thereof.

5. In an electric alarm clock, the combination comprising a toroidal coil having a central core, an outer stator element of cup shape surrounding said coil and providing peripherally spaced pairs of poles which extend axially beyond said coil, each pair including a shaded pole and an unshaded pole, a rotor mounted coaxially with respect to said core and having an outer peripheral portion magnetically coupled to said poles, a ringing pole piece comprising a flat strip of magnetic material lying flatly between said coil and said rotor and having its inner end connected to said core and providing a ringing pole at its outer end, said ringing pole piece extending radially outward between adjacent pairs of poles, the successive pairs of poles being spaced a unit distance apart around the periphery of the rotor except that the pairs of poles lying adjacent said auxiliary pole piece are spaced apart by an integral number of units greater than one, and means including an armature magnetically coupled to said ringing pole piece and mounted for vibration in response to the varying field thereof.

6. In an electric alarm clock, the combination comprising a toroidal coil having a central core, an outer stator element of cup shape surrounding said coil, and providing at its periphery a first set of poles arranged in pairs angularly spaced from one another, an inner stator element on top of said coil and providing a second set of poles arranged in pairs angularly spaced from one another, each of said pairs including a shaded pole and an unshaded pole, a rotor symmetrically mounted for rotation adjacent the respective sets of poles, a ringing pole piece lying between said coil and said rotor and extending radially outward between adjacent pairs of poles, said pole piece having its inner end connected to said core and providing a ringing pole at its outer end, the successive pairs of poles on said outer and inner stator elements being spaced a unit angular distance apart except that the pairs of poles on said outer stator element and lying adjacent said ringing pole piece are spaced apart by an integral number of units greater than 1, and means including an armature magnetically coupled to said ringing pole piece and mounted for vibration in response to the varying field thereof.

7. In an electric alarm clock, the combination comprising a synchronous electric motor stator structure having a toroidal energizing coil with a central core, two complemental pole piece assemblies respectively of pposite instantaneous polarities and together providing a hollow structure in which said energizing coil is located; a rotor unit extending adjacent both of the complemental pole pieces of the stator structure in position to be synchronously rotated thereby; a first pole piece magnetically coupled to one end of the central core and extending radially outward therefrom; a second pole piece magnetically coupled to the opposite end of said central core and extending outward in spaced relationship to said first pole piece between adjacent pairs of poles on said cup-shaped pole piece assembly; and an armature magnetically coupled to said pole pieces and mounted for vibration with respect thereto.

8. An electric alarm clock, including in combination a synchronous motor stator structure having a toroidal coil with a central core, a cup-shaped stator assembly receiving the said toroidal coil, a second stator assembly extending across the otherwise open end of the said cup shaped stator assembly, said second stator assembly providing a set of poles with unit angular spacing between poles, said cup-shaped stator assembly providing a complementary set of poles with one less pole than said second stator assembly, with said poles at substantially the same angular spacing as the second stator assembly except that two poles are spaced apart by greater than unit angular spacing, a rotor unit extending adjacent both of the complemental sets of poles of the stator structure in position to be synchronously rotated thereby; a ringing pole piece positioned between the coil and the second stator assembly and extending radially outward between the two poles spaced apart by more than unit angular spacing, said ringing pole piece having its inner end magnetically connected to said central core and providing a ringing pole at its outer end, and means including an armature magnetically coupled to said ring ing pole piece and mounted for vibration in response to the varying field thereof.

9. In an electric alarm clock, the combination comprising a synchronous motor including a toroidal coil having a central core, a first stator element surrounding said coil and providing a set of spaced poles, a second stator element on top of said coil providing a set of spaced poles, said first stator element having one less pole than said second stator element, a rotor mounted for rotation in the magnetic field of both of said poles, said motor being adapted when alternating current is applied to said coil to rotate said rotor at the same synchronous speed as a motor having the same number of poles in each stator element as the present motor has in the second stator element; a ringing pole piece having one end secured to said core and extending radially outward between adjacent poles of said first stator element and providing a ringing pole on said outer end, and means including an armature magnetically coupled to said ringing pole piece and mounted for vibration in respect thereto.

10. In an electric alarm clock, the combination comprising a motor of the closed-coil type in which the coil is enclosed within the confines of the stator structure, a pair of pole pieces in the form of fiat magnetic strips extending radially outward along the sides of the coil in spaced relation to provide a pair of spaced poles lying outside the confines of said motor, means including a resiliently mounted armature arranged for vibratory movement between said poles, and means including a clock train for releasing said armature for vibration.

11. In an electric alarm clock, the combination comprising a motor of the closed-coil type, a pair of spaced pole pieces extending radially outward from said motor and providing spaced poles, an armature magnetically coupled to said spaced poles and mounted for vibration with respect thereto, an extension on one of said pole pieces extending into the region of the opposite pole piece but substantially spaced from said armature, and an indicator having a magnetic element mounted for movement between an attracted position adjacent said pole extension and a released position for indicating disruption of current to said motor.

References Cited in the file of this patent UNITED STATES PATENTS 2,008,105 Lawrence July 16, 1935 2,417,254 Kelly Mar. 11, 1947 2,430,782 Poole NOV. 14, 1947 2,528,247 Sawyer Oct. 31, 1950 

